The present application is based on and claimed priority under 35.U.S.C. └119 with respect to Japanese Patent application No. 2001-371912 filed on Dec. 5, 2001, the entire content of which is incorporated herein by reference.
1. Field of the Invention
This invention generally relates to a valve timing control device for controlling valve opening-closing timing of an engine that is installed in a vehicle and the like.
2. Description of the Related Art
Conventionally, a valve timing control device (Laid Open Japanese Patent No. 2001-41012, etc.) for controlling valve opening-closing timing of an engine in accordance with a driving condition of the engine is disclosed. This device includes the first rotary member for rotating integrally with a crank shaft of an engine, the second rotary member engaged with the first rotary member so as to form a fluid pressure chamber between the first rotary member and the second rotary member and rotating integrally with the cam shaft of the engine, a vane provided in the first rotary member or the second rotary member and separating the fluid pressure chamber into a retard angle chamber and an advance angle chamber; a relative rotation control mechanism for locking a relative rotation phase between the first rotary member and the second rotary member in an intermediate phase between the most retarded angle phase and the most advanced angle phase; and a hydraulic circuit having the first path for moving the relative rotation phase between the first rotary member and the second rotary member in the range between the most retarded angle phase and the most advanced angle phase by supplying or discharging oil to or from the advance angle chamber or the retard angle chamber at the time of releasing the lock condition.
With regard to the conventional invention, since the relative rotation phase between the first rotary member and the second rotary member can be adjusted between the most retarded angle phase and the most advanced angle phase in accordance with the driving condition of the engine, timing of opening-closing the engine can be controlled. Further, when the relative rotation phase becomes the intermediate phase between the most retarded angle phase and the most advanced angle phase, the device is set so as to improve the efficiency of starting the engine. Then, the relative rotation phase can be locked at the intermediate phase between the most retarded angle phase and the most advanced angle phase and thus the efficiency of starting the engine can be improved.
According to the above mentioned conventional technology, a relative rotation control mechanism has the first path for moving the relative rotation phase between the first rotary member and the second rotary member in a range between the most retarded angle phase and the most advanced angle phase by supplying or discharging oil to or from the advance angle chamber or the retard angle chamber, a lock portion for locking the relative rotation phase between the first rotary member and the second rotary member in the intermediate phase between the most retarded angle phase and the most advanced angle phase, and a lock oil passage for actuating the lock portion by oil pressure.
According to the above mentioned conventional technology, oil of the first path for supplying oil to or discharging oil from the retard angle chamber or the advance angle chamber is introduced into a lock oil passage directly.
Oil pressure of the advance angle chamber or the retard angle chamber connected to the first path may fluctuate by a cam fluctuation torque. In the above prior device, since the oil of the first path is introduced into the lock oil passage, the oil pressure in the lock oil passage is affected by the fluctuation of the oil pressure in the first path and thereby the operation of the lock portion gets unstable. Therefore, it is impossible to operate the lock portion for improving an ability of starting the engine next in time.
The present invention is achieved by progressing further the above prior art, the efficiency of discharging oil of the lock oil passage can be improved when the relative rotation phase is locked by the engine halt signal. The object of the present invention is to provide the valve opening-closing timing control device capable of locking the relative rotation phase rapidly at the intermediate phase, even if the revolving speed of the engine decreases.
A valve timing control device of the present invention is characterized in that, for the device having a first rotary member for rotating integrally with one of a cam shaft and a crank shaft of an engine; a second rotary member being engaged with the first rotary member so as to form a fluid pressure chamber between the first rotary member and the second rotary member and rotating integrally with another member of the cam shaft and the crank shaft of the engine; a vane being provided in the first rotary member or the second rotary member and separating the fluid pressure chamber into a retard angle chamber and an advance angle chamber; and a relative rotation control mechanism having a first path for moving a relative rotation phase between the first rotary member and the second rotary member in a range between a most retarded angle phase and a most advanced angle phase by supplying or discharging oil to or from the advance angle chamber and/or the retard angle chamber, a lock portion for locking a relative rotation phase between the first rotary member and the second rotary member in an intermediate phase between the most retarded angle phase and the most advanced angle phase, and a lock oil passage for actuating the lock portion, the device of the present invention includes: a second path, which is provided separately from the first path and connected to the lock oil passage, for supplying or discharging oil to or from the lock oil passage; and a control means for discharging oil from one or both of the retard angle chamber and the advance angle chamber based on an engine halt signal and performing a drain operation for discharging oil from the lock oil passage through a second path.
With regard to the valve opening-closing timing control device of the present invention, oil is supplied to and/or discharged from the retard angle chamber or the advance angle chamber through the first path. Accordingly, the relative rotation phase between the first rotary member and the second rotary member can be moved in the range between the most retarded angle phase and the most advanced angle phase. If the relative rotation phase between the first rotary member and the second rotary member is moved to the intermediate phase between the most retarded angle phase and the most advanced angle phase, the lock portion locks the relative rotation phase.
Oil is supplied to and/or discharged from the lock oil passage through the second path provided separately from the first path. Since the second path is provided separately from the first path, while the fluctuation of the oil pressure of the retard angle chamber and the advance angle chamber can be avoided, the efficiency of discharging oil of the lock oil passage can be improved, at the time of locking the relative rotation phase at the intermediate phase by the engine halt signal. Therefore, even if the revolving speed of the engine decreases since the engine is stopped by the engine halt signal, the relative rotation phase can be locked at the intermediate phase rapidly and excellently.